Hans-otto Hoppen - Academia.edu (original) (raw)

Papers by Hans-otto Hoppen

Experimental and Clinical Endocrinology & Diabetes, 1993

Theriogenology, 1994

Baseline concentrations of LH and testosterone (T) in blood, their pulses, and LH and T response ... more Baseline concentrations of LH and testosterone (T) in blood, their pulses, and LH and T response to GnRH (5pg/kg) treatment were corn beagles and in 2 sexually dysfuncuonal dogs. The intact 1 ared in 19 sexually sound male eagles were allocated to 4 groups according to age, which ran ed from pubertal 7-mo-old animals to 11-yr-old adults. Baseline concentrations of b and T were measured eve for a further 3 h following challenge with GnRH. Both LIY 15 min for a period of 6 h and and T were released in a g ulsatile fashion with a wtde range of etween the LH and T pulses ranged rom 30 to 60 min, with no significant difference P ulse frequency and amplitude. The time intervals between groups. However, LH concentrations were significantly higher (P < 0.01) and T values were markedly lower in the 7-mo-old Following GnRH administration, LH peake B ubertal dogs than in the other age groups. within significant1 15 to 30 min in all the ammals, with a occurred 1 T higher increase occurring in the pubertal group (P < 0.05). Peak T values to 105 min after the LH peaks, with no clear increases occurrin in the pubertal dogs. In the 2 sexually d GnRH treatment; however, T v a! sfunctional animals, LH levels increased ollowing d ues remained extremely low both before and after treatment, indicating loss of Leydig cell function.

Hoppe-Seyler´s Zeitschrift für physiologische Chemie, 1976

Hoppe-Seyler´s Zeitschrift für physiologische Chemie, 1974

[4-14 C]Oestradiol was incubated with The 2-substituted oestrogens were found to be the rat liver... more [4-14 C]Oestradiol was incubated with The 2-substituted oestrogens were found to be the rat liver slices. Under the protection of ascorbic main metabolites (42%), present in both the lipoacid the incubation mixture was separated into the philic and water-soluble fractions. 2-Hydroxylipophilic and water-soluble (sulphate, glucuronide, oestradiol (8 %) and 2-hydroxyoestrone (16 %), preand glutathione thioether)fractions. Using different dominantly conjugated as sulphates, glucuronides Chromatographie (paper and column chromato-and glutathione thioethers, were identified as the graphy, high-voltage paper electrophoresis) and main intermediary products. The isomeric monohydrolytic procedures 21 metabolites (representing methyl ethers of the 2-hydroxylated oestrogens were 55 % of the incubated radioactivity) were isolated also important metabolites (16%): 2-Methoxyand identified by mass spectrometry. oestrogens were detected mostly in the free steroid * Presented in part at the Joint Meeting of the Biochemical Societies, Düsseldorf, October, 1974.

Journal of reproduction and fertility. Supplement, 2000

The effects of dopaminergic and opioidergic systems on LH and prolactin release in Pony mares wer... more The effects of dopaminergic and opioidergic systems on LH and prolactin release in Pony mares were investigated. Experiments were performed in intact mares during the non-breeding and the breeding seasons and in ovariectomized mares in November, March and May. Mares were treated with the dopamine D2-antagonist sulpiride, the opioid antagonist naloxone and naloxone plus sulpiride and saline. Naloxone alone and in combination with sulpiride increased plasma LH concentrations in intact anovulatory mares and in cyclic luteal phase mares, whereas sulpiride alone had no effect. None of the treatments influenced LH release in follicular phase mares. Naloxone administration significantly increased LH release in ovariectomized mares at all times of the year, the effect being most pronounced in March. Sulpiride administration increased plasma prolactin concentrations at all times of the year and was most pronounced in cyclic mares, whereas naloxone administration did not affect prolactin secr...

Veterinary Clinical Pathology, 2012

Theriogenology, 2006

To investigate seasonal effects on the efficacy of estrus synchronization in mares, we administer... more To investigate seasonal effects on the efficacy of estrus synchronization in mares, we administered a progesterone-releasing device (PRID TM) intravaginally to eight Haflinger mares for 11 days. In January 3 of 8 mares responded to the treatment with estrus and ovulation, in March 7 with estrus and 6 of 7 mares with ovulation, in June 6 of 7 and in October 7 of 8 mares with estrus and ovulation. Follicle distribution patterns at PRID TM insertion were different between January/October, March/ June and June/October (P < 0.05). Number of follicles decreased during PRID TM treatment in January, March and June (difference of number of follicles at Day 12 minus number of follicles at Day 1: À4.2 AE 2.7, À0.9 AE 0.9 and À4.9 AE 1.5 follicles), while it increased in October (3.9 AE 1.2 follicles; P < 0.05). Mean progesterone concentrations were lowest in January (0.3 AE 0.1 ng mL À1) 1) when compared with March (3.5 AE 1.8 ng mL À1 ; P = 0.063), June (4.4 AE 1.4 ng mL À1 ; P < 0.05) and October (2.2 AE 0.9 ng mL À1 ; P < 0.05). At Day 2 of PRID TM treatment, mean progesterone concentrations significantly increased in all mares. Except from January, mean LH concentrations decreased within one day after PRID TM insertion and remained at low levels during treatments in www.journals.elsevierhealth.com/periodicals/the

Reproduction in Domestic Animals, 2002

In the non-breeding season, LH release is reduced via dopaminergic systems in the ram. On the oth... more In the non-breeding season, LH release is reduced via dopaminergic systems in the ram. On the other hand, our previous studies demonstrated an opioidergic inhibition of LH release in stallions outside the breeding season. Thus, in the present study we investigated the dopaminergic regulation of LH and prolactin secretion in stallions, considering interactions between dopamine and opioids. To achieve this, stallions (n=8) were treated with the dopamine antagonist sulpiride (0.6 mg/kg), the opioid antagonist naloxone (0.5 mg/kg), sulpiride plus naloxone or saline in December, March and June. Two hours after the respective treatments, they received a GnRH agonist. Sulpiride induced a significant prolactin release which was most pronounced in December, indicating seasonal variations in the inhibition of prolactin secretion by dopaminergic systems. Prolactin concentrations were not changed by naloxone. Neither during nor outside the breeding season, a dopaminergic regulation of LH release could be demonstrated. In contrast, naloxone caused a significant (p < 0.05) LH release, confirming an opioidergic inhibition of LH release. In conclusion, opioidergic regulation of LH and dopaminergic inhibition of prolactin secretion undergo seasonal changes. Neither during nor outside the breeding season, dopaminergic effects on LH release exist in the stallion.

Reproduction in Domestic Animals, 1999

mone beim Hengst durch die sexuelle Aktvita Ãt beein~u)t wird[ Eine regelma Ã)ige Samenentnahme s... more mone beim Hengst durch die sexuelle Aktvita Ãt beein~u)t wird[ Eine regelma Ã)ige Samenentnahme scheint u Ã ber bisher nicht bekannte Mechanismen zu einer Hemmung der Testosteron! sekretion zu fu Ã hren\ wa Ãhrend die LH! und O Ýstradiolfreisetzung nicht so deutlich beein~u)t werden[ Copyright of Reproduction in Domestic Animals is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.

Journal of Veterinary Science, 2010

Autoantibodies against thyroxin (T4AA) and triiodothyronine (T3AA) are present in dogs with autoi... more Autoantibodies against thyroxin (T4AA) and triiodothyronine (T3AA) are present in dogs with autoimmune thyroiditis and have been reported to interfere with immunoassays. The objectives of this study were to determine the frequency of autoantibodies and to determine whether interference occurs by T4AA, using a non-immunological method (high performance liquid chromatography, HPLC) for thyroxin (T4) measurement. Based on clinical symptoms, T4 and thyroid stimulating hormone (TSH) concentration, 1,339 dogs were divided into six groups: Group 1: hypothyroid (n = 149); Group 2: subclinical thyroiditis (n = 110); Group 3: suspicious for non thyroidal illness (n = 691); Group 4: biochemical euthyroid (n = 138); Group 5: hypothyroid dogs under substitution therapy (n = 141); Group 6: healthy dogs (n = 110). The incidence of T4AA and T3AA, determined using radiometric assay, was low (0.5% and 3.8%) and higher in hypothyroid dogs compared to dogs suspicious for hypothyroidism (Group 2-4) (p＜0.05). T4AA was not detected in dogs with normal T4 and elevated TSH. T4 concentrations of T4AA positive samples determined using HPLC were comparable to results obtained by chemiluminescence immunoassay. These findings indicate that the probability of interference of T4AA leading to falsely elevated T4 concentration in the T4 assay seems to be low.

Journal of Veterinary Pharmacology and Therapeutics, 2009

There are no data available regarding the systemic (adverse) effects which might be induced by to... more There are no data available regarding the systemic (adverse) effects which might be induced by topical ⁄ dermal glucocorticoids (GCs) application in the horse. Besides their widespread use for the treatment of a variety of peripheral inflammatory disorders such as atopic dermatitis, eczemas or arthritis in the horse, their surreptitious application has become a concern in doping cases in competition ⁄ performance horses. Assessing both basal and ACTH-stimulated plasma cortisol as well as basal ACTH concentrations following application of dexamethsone-containing dermal ointment is necessary to determine influences on hypothalamus-pituitary-adrenal (HPA) axis. Ten clinically healthy adult standardbred horses (6 mares, 4 geldings) were rubbed twice daily each with 50 g dexamethasone-containing ointment on a defined skin area (30 • 50 cm) for 10 days. RIA and chemiluminescent enzyme immuno-metric assay were used to determine resting and ACTH-stimulated plasma cortisol and basal ACTH concentrations, respectively. HPA feedback sensitivity and adrenal function were measured by a standard ACTH stimulation test. Dermal dexamethasone suppressed significantly the resting plasma cortisol level (to 75-98%) below baseline (P < 0.001) within the first 2 days and decreased further until day 10. ACTH stimulation test showed a markedly reduced rise in plasma cortisol concentrations (P < 0.001 vs. baseline). Plasma ACTH level decreased also during topical dexamethasone application. The number of total lymphocytes and eosinophil granulocytes was reduced, whereas the number of neutrophils increased. No significant change of serum biochemical parameters was noted. Dermal dexamethasone application has the potential to cause an almost complete and transient HPA axis suppression and altered leukocyte distribution in normal horses. The effects on HPA axis function should be considered in relation to the inability of animals to resist stress situations. The data further implicate that percutaneously absorbed dexamethasone (GCs) may cause systemic effects relevant to 'doping'.

International Journal of Gynecology & Obstetrics, 1986

Citations from the Literature transfer (ET) and will permit early discrimination between normal a... more Citations from the Literature transfer (ET) and will permit early discrimination between normal and abnormal IVF pregnancies. A single beta-hCG determination on day 9 after ET may discriminate chemical, ectopic pregnancy or impending miscarriage from a normal gestation. An hCG determination on day 17 will predict early normal development of an IVF pregnancy.

Chemische Berichte, 1968

Uber einige siliciumorganische Derivate des S.S-Dimethylsulfodiimins') Aus dem Anorganisch-Chemis... more Uber einige siliciumorganische Derivate des S.S-Dimethylsulfodiimins') Aus dem Anorganisch-Chemischen Institut der Universitat Bonn (Eingegangen am 1. Marz 1968) Die Darstellung von drei siliciumorganischen Derivaten des Dimethylsulfodiimins, darunter zwei Cyclosilazane, wird beschrieben. Die Eigenschaften der neuen Verbindungen werden mitgeteilt. Seit der Darstellung der S.S-Dialkyl-sulfodiimine 2-4) wurden zahlreiche Derivate dieser Stoffklasse beschrieben, in denen der Iminwasserstoff durch Halogenes), phosphor-5.6) oder schwefelorganische 5,7*1) Reste substituiert ist. Im Zusammenhang mit spektroskopischen Untersuchungen uber die S-N-Bindung in diesen Verbindungen interessierten wir uns fur siliciumorganische Derivate des Dimethylsulfodiimins. Sie konnen bequem aus Dimethylsulfodiimin durch HC1-Kondensation mit Chlorsilanen oder durch NH3-Kondensation mit Disilazanen gewonnen werden. N.N'-Bis(trimethylsilyI)-S.S-dimethyl-sulfodiimin (1) erhalt man leicht durch Einwirkung von Chlortrimethylsilan auf Dimethylsulfodiimin in siedendem Benzol in Gegenwart der Hilfsbase Triathylamin: (CH&S(NH)z + 2 (CH,),SiCl + 2 (CZH&N-H3C, F H 3 (CH,),Si-N=S=N-Si(CI-I,), + 2 (C2H5),NH]+C1-1

Acta Endocrinologica, 1973

Animal Reproduction Science, 2007

In the present study, we investigated the effects of reproductive status, size of follicles and p... more In the present study, we investigated the effects of reproductive status, size of follicles and plasma progesterone concentrations of mares at PRID TM insertion on the efficacy of the treatment, estrous cycle patterns, plasma concentrations of progesterone and LH. The progesterone-releasing device (PRID TM) was administered intravaginally to 28 Haflinger mares for 11 days at different reproductive stages: anestrus (n = 6), estrus (n = 11) and diestrus (n = 11). Plasma concentrations of progesterone at insertion (Day 1) of PRID TM differed among treatment groups (anestrus: 0.2-0.6 ng mL −1 , estrus: 0.2-0.5 and diestrus: 1.6-10.8 ng mL −1 ; P < 0.001). Total secretion of progesterone (area under curve (AUC)) during treatment period revealed highest values in diestrus (38.2 ± 3.1 ng mL −1 h −1) followed by estrus (25.1 ± 2.7) and anestrus (21.0 ± 0.4 ng mL −1 h −1 ; P < 0.05). Progesterone area under curve (AUC) was positively correlated with initial progesterone concentrations (R = 0.5; P < 0.05), but it did not correlate with the interval from PRID TM removal to ovulation. Plasma concentrations of LH during treatment period, were significantly lower in anestrous mares (184.6 ± 28.6 ng mL −1 h −1) when compared to estrous and diestrous mares (349.7 ± 53.3 and 370.5 ± 40.3 ng mL −1 h −1 ; P < 0.05). Follicular size at PRID TM insertion had no effects on the intervals from PRID TM removal to subsequent estrus and ovulation. Follicle diameters at removal of PRID TM were significantly correlated with the interval from coil removal to estrus (R = −0.55, P < 0.05) and ovulation (R = −0.72, P < 0.0004) in cyclic mares. In anestrus 0 of 6 (0%) mares, in estrus 5 of 11 (45.5%) and in diestrus 6 of 11 (54.5%) mares ovulated within a defined interval of 1 day before to 1 day after mean interval from PRID TM removal to ovulation. In cyclic mares, response to treatment was signif

Magnetic Resonance in Chemistry, 1990

The 13C NMR spectra of eight norethisterone derivatives are presented. Substituent chemical shift... more The 13C NMR spectra of eight norethisterone derivatives are presented. Substituent chemical shifts for the methyl group at C‐18, the methylene group at C‐11 and the Δ15 double bond are evaluated and discussed.

Neurochemical Research, 1992

Concentrations of 11 amino acids, including the neurotransmitters GABA, glutamate, aspartate, gly... more Concentrations of 11 amino acids, including the neurotransmitters GABA, glutamate, aspartate, glycine and taurine, were determined in 12 brain regions of female rats during different stages of the estrous cycle. In addition, amino acids and sex hormone levels were determined in plasma. All sample collections were done in the forenoon between 9 and 11 a.m. Most regional amino acid levels measured did not change signficantly during estrous cycle, but significant alterations were found for GABA and glutamate in hypothalamus. Both amino acids were slightly decreased in hypothalamus during proestrus, which might reflect an alteration of GABA turnover in response to the high estrogen levels during this stage. A decreased glutamate level during proestrus was also found in thalamus, while both glutamate and GABA did not vary throughout estrous cycle in any of the other examined regions, including substantia nigra, amygdala, striatum, cortex and hippocampus. When diestrus was subdivided according to progesterone levels, high levels of this hormone seemed to be associated with effects on metabolism of certain amino acids, including glycine in substantia nigra, alanine in thalamus and threonine in pons/medulla. However, the few changes in regional amino acid concentrations found during the estrous cycle were so small that the functional significance of these changes cannot be ascertained without further determination of the cellular or subcellular compartments of brain tissue involved.

Movement Disorders, 1995

In some kinds of idiopathic dystonia, including paroxysmal dystonia, a role of sex hormones has b... more In some kinds of idiopathic dystonia, including paroxysmal dystonia, a role of sex hormones has been suggested because of female predominance and onset, recurrence, or exacerbation of dystonic symptoms with pregnancy. Similar effects of pregnancy have recently been reported in a model of paroxysmal dystonia, the genetically dystonic hamster. Dystonia in mutant hamsters of both genders is transient, i.e., exhibits spontaneous remission at around puberty, strongly suggesting involvement of gonadal sex hormones. For exploration of the role of sex hormones in dystonia, we undertook a series of ontogenetic experiments in male and female dystonic hamsters. Mutant animals of both genders exhibited the same postnatal development of dystonia with maximum seventy of dystonic attacks between weaning and -40 days of age and spontaneous remission thereafter. As shown by plasma sex hormone determinations and, in females, vaginal cytology, spontaneous improvement of the movement disorder coincided with puberty in both genders. Male and female hamsters had about the same plasma levels of progesterone. Compared with nondystonic hamsters, onset of puberty was significantly retarded in both male and female dystonic hamsters. Furthermore, body weight gain was lower in dystonic animals, indicating retarded postnatal development. Gonadectomy at time of weaning did not alter the age-dependent development and remission of dystonia, suggesting that gonadal sex hormones are not critically involved in the disease in hamsters. We propose that transient paroxysmal dystonia in mutant hamsters is caused by postnatal retardation of brain development resulting in a temporary impairment of brain functions with spontaneous remission independent of gonadal sex hormones. In view of the fact that the brain can synthesize steroids such as progesterone independent of peripheral glands in both genders, such neurosteroids might be involved in the postnatal brain maturation that leads to remission of dystonia at around puberty in mutant hamsters.